Machines such as, rope shovels typically include an implement, such as a dipper, for loading and unloading materials. The dipper may include a door that closes a rear of the dipper to hold the materials that are loaded into the dipper. Further, the door is opened to unload the contents of the dipper at a desired location. The door may be typically held closed by a latch mechanism. The latch mechanism may be released to allow the door to swing open under its own weight and the weight of the contents of the dipper. The door may be re-latched as the door rotates back in preparation for its next loading cycle.
During the swinging movement, the door may tend to hit against walls of the dipper or any other proximal component. Sudden opening and closing of the door may also cause wear to components associated with the door. Typically, dippers may be equipped with a braking device on the door linkage to reduce a swing speed as the door swings towards an open and/or closed position.
Conventional dipper door braking devices may utilize dry friction to provide a braking force. As the door swings open or close by virtue of its own weight, the braking device provides friction, thereby reducing the swing speed of the door. Heat may be generated due to friction between various components of the braking device. Further, various components of such braking devices may also be exposed to ambient conditions. Due to the heat generated during operation and exposure to ambient conditions, the braking devices may require frequent maintenance, adjustment or replacement resulting in machine downtime.
U.S. Patent Publication No. 2014/007468 (hereinafter the '468 publication) relates to a dipper assembly for a mining shovel. The dipper assembly of '468 publication includes a dipper body and a dipper door that is pivotably coupled to the dipper body, an arm, a housing coupled to one of the body and the door, and a piston. The arm includes a first end pivotably coupled to the body and a second end pivotably coupled to the door. The movement of the door relative to the body drives the arm to pivot relative to the body. The housing includes an inlet in fluid communication with a fluid source, an outlet, and a cylinder. The cylinder partially defines a pump chamber in fluid communication with the inlet and the outlet. The piston is movable within the cylinder and biased in a first direction. The pivoting movement of the arm causes the piston to move in a second direction opposite to the first direction. The movement of the piston changes a volume of the pump chamber.